Page:Popular Science Monthly Volume 28.djvu/839

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the nobler and more refined enjoyments of life, is not improving the instruments for the acquisition of his food; they deteriorate in his hands—a condition which first began to make its appearance with the invention of cooking. The reduction of the human dentition—which has been of advantage to the species in its struggle for existence—has further increased and changed to a kind of atavism or reversion, since reason, acquired with speech, has made man more and more independent of the direct effects of his natural surroundings.

Hence it is not merely from a purely zoological point of view that an inference is formed regarding the future change of the human race. Moreover, we cherish the hope—which is justified by scientific experiences—and the belief, which rests upon the same foundation, and these convince us of the sure advance of humanity, and of the gradual and general diffusion of morality, culture, and well-being among the various races of man.



CENTRAL AMERICA is probably the region of the globe in which the manifestations of volcanic and seismic phenomena are most frequent and continuous. During my residence of four years at San Salvador, 1 have been able to write the detailed history of twenty-three hundred and thirty-two earthquakes, one hundred and thirty-seven volcanic eruptions, twenty-seven ruins of important towns, and the formation of three new volcanoes. Geographically, Central America, founded on the Cordillera of the Andes, forms a connecting link between the two great continental masses through three successive isthmuses, those of Panama or Darien, Izabal, and Tehnantepec. It descends to the Atlantic in two large wedges, ending in Capes Gracias d Dios and Catocha, and rests abruptly on the nearly rectilinear coast of the Pacific. The base of the Cordillera is of primitive formation, and its western flank, with which we are concerned, is formed of Miocene and Pliocene strata, terminating with Quaternary and modern alluvions and more or less recent volcanic flows.

Parallel with this axis runs the remarkable string of volcanoes which, from Chiriqui in the State of Panama, to Soconusco in Mexico, includes not less than one hundred and forty-three volcanic mountains or craters, thirty of which are active, or have been within the three hundred and sixty-three years that separate us from the Spanish Conquest. They do not present themselves, as is generally believed, upon a straight line or along a volcanic fault, nor even on a line broken at